1. Field of the Invention
This invention generally relates to the area of low cost, high-resolution, high-throughput lithography with the potential to make structures that are below 100 nm in size.
2. Description of the Relevant Art
Optical lithography techniques are currently used to make microelectronic devices. However, these methods are reaching their limits in resolution. Sub-micron scale lithography has been a critical process in the microelectronics industry. The use of sub-micron scale lithography allows manufacturers to meet the increased demand for smaller and more densely packed electronic components on chips. The finest structures producible in the microelectronics industry are currently on the order of about 0.13 μm. It is expected that in the coming years, the microelectronics industry will pursue structures that are smaller than 0.05 μm (50 nm). Further, there are emerging applications of nanometer scale lithography in the areas of opto-electronics and magnetic storage. For example, photonic crystals and high-density patterned magnetic memory of the order of terabytes per square inch require nanometer scale lithography.
For making sub-50 nm structures, optical lithography techniques may require the use of very short wavelengths of light (for instance 13.2 nm). At these short wavelengths, few, if any, materials are optically transparent and therefore imaging systems typically have to be constructed using complicated reflective optics [1]. Furthermore, obtaining a light source that has sufficient output intensity at these wavelengths of light is difficult. Such systems lead to extremely complicated equipment and processes that appear to be prohibitively expensive. High-resolution e-beam lithography techniques, though very precise, typically are too slow for high-volume commercial applications.
One of the main challenges with current imprint lithography technologies is the need to establish direct contact between the template (master) and the substrate. This may lead to defects, low process yields, and low template life. Additionally, the template in imprint lithography typically is the same size as the eventual structures on the substrate (1X), as compared to 4X masks typically used in optical lithography. The cost of preparing the template and the life of the template are issues that may make imprint lithography impractical. Hence there exists a need for improved lithography techniques that address the challenges associated with optical lithography, e-beam lithography and imprint lithography for creating very high-resolution features.